Incandescent electric lamp



Feb. 13,1923.

- K KAMBAYASHI INCANDESCENT ELECTRIC LAMP.

FILED APR. 29.1921- Patented Feb. 13,1923.

i T L398 xazuo KAMBAYASHI, or mrzE-eun, kroro, mm;

I mcannnsenn'r riancrmoimr.

Application filed April 29,1921. seminaeeasee. I

.To ml whom it may concern:

- gen or other. inert gas of comparatively low subject of the Em Be 1t known that -I, I AZUO KAMnA YAsHI',-a eror of Japan, residing at No. 47 Uji-cho, u'ze-gun, Kyoto Province, Japan, have invented new and useful Improvements in an Incandescent Electric Lamp, of which the following is a specification.

This invention relates to an incandescent electric lamp whose bulb ,is filled with nitropressure, and whose lead wires have special devices to protect the filament and lead wires from the injurious effect of Edison effect current. It has for its object to obtain an incandescent electric lamp of'either low or high candle power with high efliciency and moderate lif It is a well knownfact that vaporization of metal at high temperature is greater in 1 vacuum than in atmosphere of inert gas. This principle was applied to electric lamps about twelve years ago, in Germany, to prevent the vaporization of filament by means of nitrogen gas filled in their bulbs. In this application, the gaseous pressure was only sufliciently high to prevent the blackening of a bulb, and consequently, it was comparatively low.

The difliculty is that, owing to low pressure of the gas, the generation of an Edison effect current takes place. An eddy current consists of an electron current and an ionic one, the former being a current due to electrons emitted from an incandescent filament, while the latter is one due to gaseous ions ionized by the above mentioned electrons. This current attacks filament and lead wires, and sometimes breaks them down. This phenomenfin is known as Edison effect.

The gaseous pressure in the Langmuir lamp is considerably high in order to prevent the generation of an Edison efi'ect current. But, if the gaseous pressure in the bulb of a lamp is comparatively high, the heat loss due to the convection of gas is great. Hence, with a comparatively high pressure of gas, a low-candle incandescent lamp with a high efficiency can not be practically obtained.

As a lamp of this type has great convection loss, the temperature of the filament must gas, of small convection-loss, I pressure must be comparatively low. But,

as mentioned before, if the gaseous pressure is comparatively low, the flow of Edison effect current starts between both terminals the gaseous of the filament- The damage due to Edison efi'ect, however, can be successfully elimi-- nated by the present invention.

- According to this invention, the gaseous pressure in the bulb of a lamp is lower than that of the Langmuirlamp,and a special attachment is provided on the lead wires to prevent the damage due to Edison effect. This lamp is neither a vacuum lamp nor a lamp which necessitates gas of comparativelyhigh pressure as the Langmuir lamp does, but is a new type permitting the use of gas at low pressure. Therefore, it may be called a semi-vacuum lamp. y

In the accompanying drawing, Fig. l is a perspective view of a lamp constructed in accordance with this invention.

Fig. 2 is a detailed View of a part shown in Fig. 1. i

Figs. 3 and 5 are two modifications of the part shown in Fig. 2, while Figs. 4 and 6 are plan views of Figs. 3 and 5 respectively.

In the figures, in which the same letters show the same or similar parts, 1 is a lead wire and 2 a filament. 3 is a conductive material of a suitable form with a large surface and a massive volume. It is fixed to each lead wire of the filament.

In the operation of a low pressure gasfilled lamp, under direct current supply, the joint of the filament of the positive pole to its lead wire is attacked by electronbombardment. On account of this bombardment the lead wire and the filament melt at the neighborhood of said joint, so that it can not last long. When the lamp is lighted with alternating current the bombardment occurs alternately at the ends of both terminals. To prevent this melting, the joints of the filament and lead wires are covered with a special conductor or conductors, for instance, such as a conical or cylindrical plate or wire shown in the figures.

It is obvious that, when electric current is passing through the filament 2, the potential of the conductor 3 is the same as that of the lead wire 1 to which it is fixed. So that the Edison efleot current which may occur between the terminals terminates at the surface of. the conductor, and the filament as well aslead wires are not injured.

Thus, the lamp is perfectly protected by this device from any damage due to Edison effect, and is rendered far more durable.

Although the temperature of the filament in this type of lamp is lower than that in the Langmuir lamp, the efficiency of the former is never lower than that of the latter on account of the smaller convection loss. Moreover, in consequence of the lower temperature of the filament, vaporization of the filament becomes less than in the Langmuir lamp. And, since the pressure of the gas in a lamp of this type is considerably high compared with that of a vacuum lamp, it is suflicient to prevent the blackening of the bulb as effectively as it is done in the Langmuir gas-filled lamp.

Claims 1. In an incandescent electric lamp, the combination of a lead wire, a filament connected thereto, anda conductor secured to said lead wire and encircling the joint between the lead wire and filament and portions of 'said lead wire and filament adjacent to said joint.

2. In an incandescent electric lamp, the combination of a lead wire, a filament connected thereto, and acoiled wire conductor secured to said lead wire and encircling the joint between the lead Wire and filament and portions of said lead Wire and filament adjacent to said joint.

3. In an incandescent electric lamp, the combination of a pair of lead wires, a filament connected at its opposite ends to said lead Wires, and a conductor secured to each of said lead wires and encircling the re spective joints between the lead Wires and the ends of the filament.

In testimony whereof I have signed my name to this specification.

KAZUO KAMBAYASI-II. 

